This week hundreds of college Republicans and men sporting Founding Father costumes are in National Harbor, Md., down the Potomac from Washington, D.C., for the Conservative Political Action Conference, the annual meeting of the American Conservative Union. Anti-tax crusader Grover Norquist calls it “Woodstock for conservatives.”

But while the American Conservative Union, CPAC’s parent, refers to itself as the “nation’s oldest and largest grassroots conservative organization,” an examination of the group’s finances shows the organization receives support from some of America’s biggest and least popular industries: guns, big oil, and cigarettes.

Rarely seen and previously unreported tax filings for the ACU and ACU Foundation, the group responsible for staging CPAC, reveal that in the 2010 tax year, the National Rifle Association provided $225,000 of the ACU Foundation’s overall revenue. In 2010 the ACU Foundation reported $288,670 in grant revenue and $1,063,103 in “program service revenue.” The NRA’s executive vice president and CEO, Wayne LaPierre, has been a regular featured speaker at past CPAC events and he again spoke at the gathering on Thursday. The 2013 CPAC included an event titled “NRA University” at which CPAC attendees could “learn more about NRA, Second Amendment, gun control debate.” It even offered participants “a FREE one-year NRA membership,” according to the conference schedule. The NRA is a “presenting sponsor” at the 2014 conference—a sponsorship level requiring a $110,000 contribution.

In 2010 the billionaire Koch brothers’ companies contributed a total of $50,000 to the ACU and the ACU Foundation. In the same year, cigarette giant Altria contributed $25,000 to the ACU, and the conservative Anschutz Foundation contributed $25,000 to the ACU Foundation.

Perhaps more importantly, the ACU promotes the tobacco industry when new regulatory measures are proposed. The ACU publicly defended the interests of the tobacco industry when the FDA proposed imposing restrictions on menthol cigarettes. Responding to a July 2013 invitation for public input from the FDA, the ACU wrote to express its “strong opposition to the establishment of the Food and Drug Administration of a tobacco product standard for menthol in cigarettes.” The ACU also used its influence to promote legislation benefiting the oil and gas industries. In addition to contributions from the Anschutz Foundation, funded by oil tycoon Philip Anschutz and the Koch brothers, Chevron contributed $20,000 to the ACU Foundation in 2010. The oil and drilling industry found no shortage of support from the ACU. In December 2011 the ACU wrote to Rep. Jim Jordan, then-chairman of the Republican Study Committee, urging Jordan and all members of the House to support the “Jobs Through Growth Act,” which would “reverse the absurd finding of EPA that carbon dioxide is a ‘pollutant.’ ” “The bill would also expedite the construction and operation of the Keystone XL Pipeline,” said the ACU letter. The bill gained 59 co-sponsors but died in committee.

Koch Industries, a major player in the U.S. oil and gas industry, sponsored the “VIP Ronald Reagan Dinner Reception” at CPAC’s 2013 meeting. (Former Koch Industries Executive Director of Federal Affairs Matt Schlapp appears as a board member on ACU tax filings starting in 2009.) CPAC’s 2014 annual conference website lists Koch and the NRA as sponsors but doesn’t disclose the precise amount of either’s support.

When contacted for comment about its corporate donors and the appearance of advocacy for the oil, cigarette, and gun industries, ACU National Communications Director Laura Keehner Rigas said, “ACU does not discuss the details of contributions beyond what is publicly available through our Form 990 and our website. Please reference our website for a sampling of CPAC sponsors, co-sponsors, and exhibitors.”

Positive PR and the appearance of “grassroots” support are much-needed by the oil and gas industry. It topped the list of most disliked industries in the United States, narrowly beating out the federal government, in an August 2012 Gallup poll. The NRA and tobacco industry have also seen their popularity suffer. The NRA’s favorability dropped to 42 percent, with 45 percent reporting an unfavorable view of the organization, in a January 2013 Public Policy Polling survey. And 22 percent of Americans support a complete smoking ban, up from 12 percent in 2007, according to a July 2013 Gallup poll.

The two industries are so contentious that even some in the largely conservative world of NASCAR are distancing themselves. In April, ESPN reported that two drivers were advised by their public relations directors to avoid doing interviews with the NRA logo behind them. NACSCAR itself, once strongly associated with tobacco sponsors, has moved on to other sponsors following the June 2010 implementation of new FDA rules ending smokeless tobacco and cigarette sponsorships for sporting events.

The gun, tobacco, and oil industries will undoubtedly continue their PR efforts. And it would seem that CPAC is the “grassroots” outreach wing of their corporate public relations strategy.